Police carrying items from the West New York home of a sister of the Boston Marathon bombing suspects on Friday, April 19, 2013.

The massive investigation into the Boston Marathon bombing took a dramatic turn into northern New Jersey on Friday, as federal agents interviewed one of the sisters of the suspects at her West New York apartment and searched for their other sister in Fairview.

About a dozen agents from the FBI spent five hours at one sister’s Buchanan Place home in West New York, leaving about 4 p.m. after questioning her, removing a computer and cellphones. Later, local police hauled away several black plastic bags full of items.

The woman was cooperating with federal investigators, said Michael E. Indri, director of police in West New York. He called her “heartbroken and shocked.”

Indri said she told investigators she had not been in contact with her brothers for some time, but officials took her computer and hand-held devices, like cellphones, to look for past communications. He did not give her name, but public records show a 22-year-old woman by the name of Ailina Tsarnaev at that address, who also goes by Amina.

No one emerged from her home after her brother’s capture Friday to talk to about a dozen members of the media clustered on the sidewalk outside the three-story apartment building.

But West New York Mayor Felix Roque went into her apartment at 9 p.m. After he left 15 minutes later, he spoke briefly, but declined to discuss the meeting.

“It’s not easy for them,” he said. “I don’t want to comment too much. This is a human tragedy. My goal as the mayor is to take care of them. They’re residents of West New York.”

Several police officers continued to stand guard outside the apartment building as of 9:30 p.m.

West New York’s connection to the investigation became public by midmorning, when a large team of FBI agents in body armor — some in blue jackets labeled Joint Terrorism Task Force — converged on her narrow street in a working-class neighborhood. Meanwhile, a manhunt continued in the Boston area for her younger brother, 19-year-old Dzhokhar Tsarnaev.

Shortly before the FBI arrived on Buchanan Place, the sister gave a brief interview to reporters through a slightly opened door of her second-floor apartment. She said she was stunned that her brothers might have been involved in a bombing that killed three people and wounded more than 170.

She referred to her younger brother as an “amazing child” and her older brother as “a great person,” “smart” and a “kind, loving man.”

“I have no idea what got into them,” she said. At one point, she also said she had “no idea” if her brothers actually committed this crime, adding that the media often reported things that proved untrue.

She would not give her name, but spoke of the grief she feels for the victims and their families.

“I’m sorry for the families that lost their loved ones the same way I lost a loved one,” she said. “I’m not OK, just like anyone else is not OK. No one is OK right now. … I want to be left alone.”

She said she had not seen or spoken with her brothers in years. A man at the door, who said he was her husband, said he had never met his wife’s relatives. “I’m not Muslim and they didn’t accept me,” he said.

Local officials said they would post a 24-hour police presence outside their home for protection, and an officer was going to bring them some formula for the baby. At times during the day, throngs of people were crushed against police barriers to see what was going on.

Vigilance urged

Late Friday afternoon, Roque told residents they didn’t have anything to be concerned about, and that there was no threat to their neighborhood.

Bergen County Executive Kathleen A. Donovan said in a release Friday afternoon that the Bergen County Police Department’s bomb squad had increased its staff and would respond to any calls about suspicious packages. She urged residents to report anything “out of place” by alerting 911 or their local police.

In Fairview early Friday, FBI agents contacted local police and the owner of a condominium apartment at 385 Kamena St.

The owner of the apartment, Oleksandr “Alex” Malyava, said he had rented it to two sisters, Bella and Ailina Tsarnaev, early last year. They moved out in January after being late on rent payments. There were a lot of complaints from neighbors and the property manager, Melody Realty, about the very loud, constant fighting that apparently went on between one of the sisters and a boyfriend, Malyava said when reached by phone Friday.

He said the FBI had contacted him. Court records show the sisters moved into Apartment 10 in March 2012. In August, Malyava filed a landlord-tenant complaint in Superior Court in Hackensack, claiming the pair owed him back rent of $1,650. The case was settled in September, with the total debt paid.

Court records also show the Bergen County Prosecutor’s Office filed a civil forfeiture case last month against 24-year-old Bella Tsarnaeva — spelled with an “a” in legal papers — and her live-in boyfriend, Ahmad Khalil. The filing said that on Dec. 11, Fairview police went to the couple’s Kamena Street apartment on a report of domestic violence. Police said Khalil claimed that Tsarnaeva scratched him.

While inside the apartment, police said, they smelled marijuana and found some drug paraphernalia and $537 in cash in a clear plastic bag hanging on a mirror, records show. When Tsarnaeva arrived and admitted slapping Khalil, she was arrested on charges of domestic violence and simple assault, according to court documents. Khalil was arrested on a charge of possession of marijuana; police said they found “a large amount” in his closet.

The Prosecutor’s Office is seeking forfeiture of the money, alleging that it was the product of criminal activity. Bergen County Prosecutor John L. Molinelli could not be reached for comment on that matter.